Magneto for model engines



Oct. 7, 1941. E. VOLLENWEIDER 2,258,503

' MAGNETO FOR MODEL ENGINES Filed Aug. 7, 1959 INVENTOR. EmilVallcnweider P LL23;

A TTORNEY Patented Oct. 7, 1941 UNITED STATES" PATENT OFFICE 1 4 i I2,258,503 I MAGNETO son MODEL memes Emu Vollenweider, Sacramento, Calif.plication sum '1, 1939, Serial No. 288,803

'9 Claims.

This invention relates in general to magneto ignition of gas engines,and in particular is directed to magneto ignition of extremely small ormidget" gas engines as are now available for use in connection withmodel'airplanes, boats and the like.

Heretofore such model engines, due to the necessity for weightlimitation, have been provided with'a small battery and coil assembly tosupply therequisite high tension ignition current. However, this type ofignition assembly is subject to the objection that the battery must befresh in order to assure proper functioning of the engine, and tomaintain a fresh battery requires frequent replacement with attendantcost and inconvenience.

It is therefore the principal object of this invention to provide amagneto for model engines which is proportionate in and weight thereto,and also is of substantially no greater weight than the battery and coilassemblies as now Another object of the invention is to provideincombination with a model engine and driven therefrom-a magneto which isarranged so that the engine may revolve at speeds limited only'by thecharacteristics of the engine.

A further object of the invention is to provide the combination of amodel engine. a driving element (such as the prcpellor mounting hub of amodel airplane), and a magneto interposed between the engine and elementin connected and driven relation therewith.

It is also an object of the invention to provide a magneto for modelairplane engines which is constructed and mounted with the engine in amannerto maintain proper balance of the en sine.

Afurther object of the invention is to produce a simple and inexpensivedevice and yet one which will be exceedingly eifective for the purposefor which it is designed.

' These objects! accomplish by meansof such Figure 3 is a frontelevatlon' of the magneto with 'the propeller hub partly broken away.

Figure 4 is an end view of the inductor rotor of the magneto.

Figure 5 is a longitudinal section on line 5-5 of Fig. 4.

Referring now more particularly to the characters of reference on thedrawing, the magneto is shown in the present instance in combinationwith a model airplane engine of usual design, and including a cylinderI, a fuel reservoir 2, a crankcase 3 formed with a projecting crankshafthearing or boss 4, and a crankshait having one end 5 extending throughboss 4 and projecting'some distance therebeyond as at to.

The magneto comprises a vertical back plate 6 having'a central openingI; a longitudinal split sleeve 8 being formed integral with the plate inregister with opening 1 and projecting axially rearward. This splitsleeve engages over the crankcase boss 4 and is clamped thereon by aclamping ring 8 including relatively long tightening screw ll having a.finger piece i I on the outer end thereof. The plate I and sleeve 8 areof a non-magnetic metal such as brass.

The device includes an armature. of laminated silicon steel, having acore surrounded by an inductance coil l2, and field pieces I: dependingfrom the ends of the-core at substantially right angles thereto; theinner edges of said field pieces defining the sides of an annular spacein the opening I, and with the col 112 in horizontal and uppermostposition. .The entire armature is thus fixed on the plate 8. The coil l2includes, as usual, primary and secondary windings which are suitablyinsulated and disposed about the core between dielectric end plates Ii.

The projecting portion Ia of the crankshaft extends through plateopening'l and axially through the annular space between field pieces It; saidcrankshaft portion 5a terminating some distance forwardly of thearmature. Theforward end of the crankshaft is cut with threads as at itand a nut I1 is threaded thereon.

An inductor rotor is mounted on crankshaft portion In for rotationbetween the field pieces Q It. This rotor, as shown in detail in Figs. 4

and 5, comprises, as a unit, radially opposed pole shoes 18 of siliconsteel, parallel magnets ll extending between corresponding ends of thepole shoes, a substantially rectangular center section out to the cam.

From the foregoing description it will be readily 75 or core 2| ofnon-magnetic metal, and vertical.

front and rear face plates II and 22 respectively of non-magnetic metal;said plates lapping over the outer edges of magnets I. as at 23. Theassembly is secured together by cross rivets II. A hub II-projectsforwardly from the core Ill aseasos seen that I have produced such adevice as substantially fulfills the objects of the invention as setforth herein.

-While this specification sets forth in detail the I present andpreferred construction of the device.

of the rotor, and the outer end of said hub being enlarged to form anannular propeller mounting fiange It. The rotor core II, front faceplate 2i, hub 26, and fiange 20 are formed in- "Ihe projecting portionis of the crankshaft extends axially through the rotor core 20 and hubfl, the rotor and crankshaft being secured against relative rotation bya squared shaft porsocke't 2| in the rear tion 21 seated in a square endof the rotor.

' The. timing mechanism for the magneto com- .1. A. magneto structurefor direct driveby the crankshaft of an engine, said engine having a iscrankcase provided with an exterior boss surprises a supporting bracket2! of non-magnetic so rotatable masneto unit mounted tn and sup- -rnetalmounted by bolts it above hub fl and between the field pieces it. Onebreaker point 80 is mounted on bracket. in insulated relation, while thecooperating breaker point ll is carried on the adJacent-end of adielectric lever If pivoted intermediate its ends as at 38 on bracket 20andactuated at the other end by a cam 34 on hub ll. As is obvious, thepoints make and as 2..A magneto structure for direct drive by the breakwith rotation of the rotor and the included hub is. a leafspring as isfixed with thelever. andpointll andarrangedsoastoengageastop II undertension and sees to urge the normally open points together; this springalso serving as a ground lead.

The high tension lead 81 of coil II is connected with the spark plug Pof the engine, while one primary lead II is connected with the fixedpoint ll, and the other primary lead II is grounded on the adjacentfield piece. 1

The above described magneto needs no condenser connected between thepoints due problatter projects: a sup rounding the crankshaft, andbeyond which the member adjacent the outer end of the boss, a sleeve onsaid member engaging and secured on the boss, anonported by said memberandincluding opposed field pieces and a magneto rotor fixed on theprojecting portion of the crankshaft between the field pieces.

crankshaft of an engine, said engine having a crankcaseprovided with anexterior boss surrounding the crankshaft and beyond which the latterprojects, a member surrounding and turnso able on the boss, a stationarymagneto unit including opposed field pieces supported by said member, amagneto rotor fixed on the projecting portion of the'crankshaft betweenthe field pieces and means applied to the sleeve to adjustably as holdthe same against rotation-on the boss.

ablytothesmallsizeofcoil l2;aninherentcspacity being created which doesaway with the necessity of a condenser. As no condenser is used, themagneto functions properly at very high speeds and which could not occurif a condenser were used as the charging and dlscharging thereof limitsthe speed at which a magneto can function. A model engine with mymagneto as the ignition source can revolve at speeds much in excess ofsimilar engines with battery ignition.

In use, the propeller (not shown) fits on crankshaft portion lo andabuts against fiange it; the nut il holding the propeller securely inengagement with said fiange. With actuation of the engine,'the magnetorotor and propeller rotate at the same speed: rotation of said magnetorotor producing the ignition current.

- to the axis thereof and in which openings wicks "are disposed.

Oil from within the crankcase feeds but slowly between the crankshaft land boss [onto the adjacent ends ofsaid wicks and thence is fed to theother ends of the wicks and 8. A magneto structure for direct drive bythe crankshaft of an engine. said engine having a crankcase providedwith an exterior'boss surrounding the crankshaft and beyondwhich the.

latter projects; aradial supporting plate having a rearwardly extendingsleeve into 'which the boss projects, a magneto part mounted'on theplate, a cooperating part mounted on and driven means securing thesleeve on the boss.

4. A magneto structure for direct drive by the crankshaft of an engine,said engine having a crankcase provided with an exterior boss sur-.rounding the crankshaft'and beyond which the latter projects;' a radialsupporting plate having a rearwardly extending sleeve turnably encasingthe boss, a magneto (part mounted on the plate, a cooperating magnetopart mounted on and driven by'the projecting portion of the crankshaft,and a clamping collar surrounding the sleeve, the latter being splitlongitudinally under the collar. q

5. A magneto structure for direct drive by the crankshaft of an engine,said engine having a crankcase from which the crankshaft projects, astationary magneto unit including'opposed field pieces fixed with thecrankcase, a rotor fixed on the projecting portion of the shafttocooperate with said field pieces, a make andbreak ignition controldevice supportedon said unit, a hub on the rotor projecting axiallytherefrom, and a cam on said hub to actuate the device. v

6. In an engine driven magneto, .a drive shaft.abossinwhichsaidshaftisiournaledandbeyond' the outer end of which theshaft projects, the inner end of theboss'being exposed to a lubricantfor the journaled portion of the shaft, a magneto rotor fixed on theshaft beyondthe boss, a make and break ignition control devicebeyondtherotor,acamiixedwiththerotorto attests actuate said device andmeans to feed the lubricant from the outer end of the boss past therotor and onto the cam.

7. In an engine driven magneto, a drive shaft, a boss in which saidshaft is journaled and beyond the outer end of which the shaft projects,the inner end of the boss being exposed to a lubricant for the Joumaledportion of the shaft, a magneto rotor fixed on the shaft beyond butimmediately adjacent the boss, the portion of the shaft on which therotor is mounted being reduced in diameter, a make and break ignitioncontrol device mounted adjacent and beyond the rotor, a cam fixed withthe rotor to actuate the device, the rotor having a passage therethroughfrom end to end and whose radially inner edge is substantially alinedwith the bore or-tiie boss,

and a wick in said passage.

8. In the combination of a model airplane ensine and an engine actuatedmagneto, said engine having a crankcase and a crankshaft projecting atone end from the crankcase and having an outer end portion adapted forconnection with a propeller; said magneto including an inductor rotorsecured on the projecting portion of the shaft between the crankcase andsaid outer end portion of the shaft.

